1. Technical Field
The present invention relates to a method for manufacturing a piezoelectric actuator that includes piezoelectric elements and lead electrodes on a diaphragm. The piezoelectric actuator includes individual electrodes and piezoelectric layers formed of a piezoelectric material. The lead electrodes are connected to the corresponding individual electrodes.
2. Related Art
Some known piezoelectric actuators include piezoelectric elements and lead electrodes on a diaphragm. Each of the piezoelectric elements includes a lower electrode, a piezoelectric layer, and an upper electrode. The lead electrodes are connected to electrodes of the piezoelectric elements. Some known piezoelectric elements include a piezoelectric layer formed of a piezoelectric material having an electromechanical transfer function, such as crystallized piezoelectric ceramic, between a lower electrode and an upper electrode.
Such piezoelectric actuators, called flexural vibration mode piezoelectric actuators, are used in liquid-ejecting heads, for example.
One example of liquid-ejecting heads is an ink jet recording head. The ink jet recording head has a diaphragm as a portion of a pressure-generating chamber. The pressure-generating chamber communicates with a nozzle opening through which ink droplets are ejected. A piezoelectric element deforms the diaphragm to pressurize ink in the pressure-generating chamber, thereby ejecting ink droplets from the nozzle opening.
Piezoelectric actuators and liquid-ejecting heads can be manufactured by forming a plurality of piezoelectric actuators and liquid-ejecting heads on a single wafer and subsequently dividing the wafer into piezoelectric actuators and liquid-ejecting heads.
One group of the electrodes of the piezoelectric element can serve as individual electrodes, and the other group can serve as a common electrode. JP-A-2007-73931 discloses an actuator in which upper electrodes serves as individual electrodes, and lead electrodes are formed on the upper electrodes.
JP-A-2007-234667 discloses a method for removing a natural oxidation film formed on a semiconductor substrate wafer by sputter etching.
In the formation of lead electrodes on individual electrodes, however, the sputter etching of the individual electrodes to remove contaminants from the individual electrodes may cause the buildup of electric charges on the isolated individual electrodes, resulting in charging.
The degree of charging varies with the piezoelectric actuator and the position in the wafer, affects the characteristics of each piezoelectric element, and causes variations in the hysteresis characteristics of a piezoelectric layer in each piezoelectric element. Variations in the hysteresis characteristics of a piezoelectric layer also cause variations in the deformation characteristics of the piezoelectric actuator.